GATA2 deficiency and human hematopoietic development modeled using induced pluripotent stem cells

Abstract

GATA2 deficiency is an inherited or sporadic genetic disorder characterized by distinct cellular deficiency, bone marrow failure, various infections, lymphedema, pulmonary alveolar proteinosis, and predisposition to myeloid malignancies resulting from heterozygous loss-of-function mutations in the GATA2 gene. How heterozygous GATA2 mutations affect human hematopoietic development or cause characteristic cellular deficiency and eventual hypoplastic myelodysplastic syndrome or leukemia is not fully understood. We used induced pluripotent stem cells (iPSCs) to study hematopoietic development in the setting of GATA2 deficiency. We performed hematopoietic differentiation using iPSC derived from patients with GATA2 deficiency and examined their ability to commit to mesoderm, hemogenic endothelial precursors (HEPs), hematopoietic stem progenitor cells, and natural killer (NK) cells. Patient-derived iPSC, either derived from fibroblasts/marrow stromal cells or peripheral blood mononuclear cells, did not show significant defects in committing to mesoderm, HEP, hematopoietic stem progenitor, or NK cells. However, HEP derived from GATA2-mutant iPSC showed impaired maturation toward hematopoietic lineages. Hematopoietic differentiation was nearly abolished from homozygous GATA2 knockout (KO) iPSC lines and markedly reduced in heterozygous KO lines compared with isogenic controls. On the other hand, correction of the mutated GATA2 allele in patient-specific iPSC did not alter hematopoietic development consistently in our model. GATA2 deficiency usually manifests within the first decade of life. Newborn and infant hematopoiesis appears to be grossly intact; therefore, our iPSC model indeed may resemble the disease phenotype, suggesting that other genetic, epigenetic, or environmental factors may contribute to bone marrow failure in these patients following birth. However, heterogeneity of PSC-based models and limitations of in vitro differentiation protocol may limit the possibility to detect subtle cellular phenotypes.

Transcriptional regulation of lysophosphatidic acid receptors 2 and 3 regulates myeloid commitment of hematopoietic stem cells

“…2F, left) and megakaryocytic genes (Fig. 2F, right), which is consistent with previous findings in human induced pluripotent stem cells (20). Furthermore, overexpression of GATA-1 inhibited the expression level of GATA-2 (Fig.…”

Secondary leukemia in patients with germline transcription factor mutations (RUNX1, GATA2, CEBPA)

“…GATA2 2/2 human iPSC have almost completely abolished hematopoietic differentiation with a significant reduction in hematopoietic stem and progenitor cells (HSPCs), whereas GATA2 2/1 lines have a smaller reduction in HSPCs. 142 For RUNX1, iPSC generated from patients with different mutations confirmed the haploinsufficient baseline megakaryocyte defects that manifest as frequent thrombocytopenia in humans carriers, and cells with duplication of the RUNX1 mutation (trisomy 21) or "dominantnegative" missense mutations were associated with increased HSCs and granulocyte-monocyte progenitors, respectively, suggesting an additional functional step toward leukemia. 57,143 This supports that the degree of reduction in gene activity is an important contributor to the predisposition and progression to leukemia, a concept that is clearly illustrated by the frequency of second somatic mutations in the leukemic progression of germline RUNX1-and CEBPA-mutated disorders.…”

Patient iPSC-Derived Macrophages to Study Inborn Errors of the IFN-γ Responsive Pathway

“…Of note, also non-hematopoietic cells have been successfully used here to explain susceptibility to herpes simplex virus 1 in the central nervous system [9], influenza pneumonitis [10,11] or viral myocarditis. Cells have been differentiated into megakaryocytes to study thrombocytopenia [12]; erythrocytes to model sickle cell disease [13]; hematopoietic progeny and NK cells to study GATA2 deficiency [14] and macrophages to model such diverse diseases as hereditary pulmonary alveolar proteinosis [15], familial Mediterranean fever [16] and Gaucher disease [17]. Patient-specific macrophages are of high interest, as these cells are important mediators in innate and adaptive immunity and tissue homeostasis and are involved in a variety of functions both in disease and health [18].…”